omap: Update omap3_defconfig to work with SMP_ON_UP

With the recent changes to core ARM kernel code, we can now
boot SMP kernel on UP systems. Update omap3_defconfig to
enable SMP. This allows us to remove omap_4430sdp_defconfig.

In addition to enabling SMP, we also need to disable some
options to make the system boot:

- For some reason LOCK_STAT causes tons of
  WARNING: at mm/percpu-vm.c:320 pcpu_alloc+0x2fc/0x888()
  so disable it for now.

- MUSB init fails for multi-omap, disable it for now.

- LOCAL_TIMERS hangs on omap4, disable it for now.

Also disable DEBUG_LL as this should be only enabled for
debugging.

Signed-off-by: Tony Lindgren <tony@atomide.com>